Publications

Electrolytic hydrogen can support the decarbonization of the power sector. Achieving cost-effective power-to-gas-to-power (PGP) integration through targeted emissions pricing can accelerate the adoption of electrolytic hydrogen in greenhouse gas-intensive power sectors. This study develops a framework for assessing the economic viability of electrolytic hydrogen-based PGP systems in fossil fuel-dependent grids while considering the competing objectives of the electricity system operator a risk-averse investor and the government. Here we show that given the risk-averse investor’s inherent pursuit of profit maximization a break-even carbon abatement cost of at least 57 Canadian Dollars per tonne of CO₂ by 2030 from the government with a shift in electricity market dispatch rules from sole system marginal pricereduction to system-wide emissions reduction is essential to stimulate price discovery for low-cost hydrogen production and contingency reserve provision by the PGP system. This work can help policymakers capture and incentivize the role of electrolytic hydrogen in low-carbon power sector planning.

Reducing CO2 emissions is an increasingly important goal in general aviation. The dual-fuel hydrogen–kerosene combustion process has proven to be a suitable technology for use in small aircraft. This robust and reliable technology significantly reduces CO2 emissions due to the carbon-free combustion of hydrogen during operation while pure kerosene or sustainable aviation fuel (SAF) can be used in safety-critical situations or in the event of fuel supply issues. Previous studies have demonstrated the potential of this technology in terms of emissions performance and efficiency while also highlighting challenges related to abnormal combustion phenomena such as knocking and pre-ignition which limit the maximum achievable hydrogen energy share. However the causes of such phenomena—especially regarding the role of lubricating oils—have not yet been sufficiently investigated in hydrogen engines making this a crucial area for further development. In this paper investigations at the TU Wien Institute of Powertrain and Automotive Technology concerning the role of different engine oils in influencing pre-ignition tendencies in a hydrogen–kerosene dual-fuel engine are described. A specialized test procedure was developed to account for the unique combustion characteristics of the dual-fuel process along with a detailed purge procedure to minimize oil carryover. Multiple engine oils with varying compositions were tested to evaluate their influence on pre-ignition tendencies with a particular focus on additives containing calcium magnesium and molybdenum known for their roles in detergent and anti-wear properties. Additionally the study addressed the contribution of particles to pre-ignition occurrences. The results indicate that calcium and magnesium exhibit no notable impact on pre-ignition behavior; however the addition of molybdenum results in a pronounced reduction in pre-ignition events which could enable a higher hydrogen energy share and thus decrease CO2 emissions in the context of hydrogen dual-fuel aviation applications.

The ongoing digitalization of energy infrastructure is a crucial enabler for improving efficiency reliability and sustainability in gas distribution networks especially in the context of decarbonization and the integration of alternative energy carriers (e.g. renewable gases including biogas green hydrogen). This study presents the development and application of a Digital Twin framework for a real-world gas distribution network developed using open-source tools. The proposed methodology covers the entire digital lifecycle: from data acquisition through smart meters and GIS mapping to 3D modelling and simulation using tools such as QGIS FreeCAD and GasNetSim. Consumption data are collected processed and harmonized via Python-based workflows hourly simulations of network operation including pressure flow rate and gas quality indicators like the Wobbe Index. Results demonstrate the effectiveness of the Digital Twin in accurately replicating real network behavior and supporting scenario analyses for the introduction of greener energy vectors such as hydrogen or biomethane. The case study highlights the flexibility and transparency of the workflow as well as the critical importance of data quality and availability. The framework provides a robust basis for advanced network management optimization and planning offering practical tools to support the energy transition in the gas sector.

Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology for large-scale hydrogen production yet their industrial deployment is hindered by the harsh acidic conditions and sluggish oxygen evolution reaction (OER) kinetics. This review provides a comprehensive analysis of recent advances in iridium-based electrocatalysts (IBEs) emphasizing novel optimization strategies to enhance both catalytic activity and durability. Specifically we critically examine the mechanistic insights into OER under acidic conditions revealing key degradation pathways of Ir species. We further highlight innovative approaches for IBE design including (i) morphology and support engineering to improve stability (ii) structure and phase modulation to enhance catalytic efficiency and (iii) electronic structure tuning for optimizing interactions with reaction intermediates. Additionally we assess emerging electrode engineering strategies and explore the potential of non-precious metal-based alternatives. Finally we propose future research directions focusing on rational catalyst design mechanistic clarity and scalable fabrication for industrial applications. By integrating these insights this review provides a strategic framework for advancing PEMWE technology through highly efficient and durable OER catalysts.

The potential for hydrogen production from heavy oil reservoirs has gained significant attention as a dual-benefit process for both enhanced oil recovery and low-carbon energy generation. This study investigates the technical and economic feasibility of producing hydrogen from heavy oil reservoirs using two primary in situ combustion gasification strategies: cyclic steam/air and CO2 + O2 injection. Through a comprehensive analysis of technical barriers economic drivers and market conditions we assess the hydrogen production potential of each method. While both strategies show promise they face considerable challenges: the high energy demands associated with steam generation in the steam/air strategy and the complexities of CO2 procurement capture and storage in the CO2 + O2 method. The novelty of this work lies in combining CMG-STARS reservoir simulations with GoldSim techno-economic modeling to quantify hydrogen yields production costs and oil–hydrogen revenue trade-offs under realistic field conditions. The analysis reveals that under current technological and market conditions the cost of hydrogen production significantly exceeds the market price rendering the process economically uncompetitive. Furthermore the dominance of oil production as the primary revenue source in both methods limits the economic viability of hydrogen production. Unless substantial advancements are made in technology or a more cost-efficient production strategy is developed hydrogen production from heavy oil reservoirs is unlikely to become commercially viable in the near term. This study provides crucial insights into the challenges that must be addressed for hydrogen production from heavy oil reservoirs to be considered a competitive energy source.

This study assesses the feasibility and profitability of marine hybrid clusters combining wave energy converters (WECs) and offshore wind turbines (OWTs) to power households and marine aquaculture. Researchers analyzed two coastal sites: La Serena Chile with high and consistent wave energy resources and Ensenada Mexico with moderate and more variable wave power. Two WEC technologies Wave Dragon (WD) and Pelamis (PEL) were evaluated alongside lithium-ion battery storage and green hydrogen production for surplus energy storage. Results show that La Serena’s high wave power (26.05 kW/m) requires less hybridization than Ensenada’s (13.88 kW/m). The WD device in La Serena achieved the highest energy production while PEL arrays in Ensenada were more effective. The PEL-OWT cluster proved the most cost-effective in Ensenada whereas the WD-OWT performed better in La Serena. Supplying electricity for seaweed aquaculture particularly in La Serena proves more profitable than for households. Ensenada’s clusters generate more surplus electricity suitable for the electricity market or hydrogen conversion. This study emphasizes the importance of tailoring emerging WEC systems to local conditions optimizing hybridization strategies and integrating consolidated industries such as aquaculture to enhance both economic and environmental benefits.

Emerging energy technologies offer significant opportunities for climate change mitigation. However the assessment of their potential environmental impact through prospective life cycle assessment (pLCA) is challeng‑ ing owing to parameter uncertainties arising from data gaps temporal variability and evolving technological contexts when modeling their prospective life cycle inventories (pLCI). Existing methodologies lack standardized approaches for systematically integrating parameter uncertainty within pLCI frameworks often initially overlooking it. In order to fill this gap this study proposes a structured and transparent approach for incorporating parameter uncertainty directly into the pLCI modeling process. The goal is to enhance the robustness transparency and reproducibility of pLCI models. A decision–support flowchart based on an adapted six-step framework was developed to help life cycle assessment (LCA) practitioners address parameter uncertainty during the “goal and scope definition” and“life cycle inventory” phases of pLCA. The flowchart guides users through the process of defining of the assessment’s goal scope as well as its temporal and geographical boundaries and the technology’s maturity level (Step 1). Step 2 entails gathering data to depict the technology’s development. Steps 3 and 4 involve identifying parameters that are likely to change in the future such as manufacturing processes materials equipment and component dimensions as well as their respective uncertainties. Step 5 includes the learning effects required for industrial-scale production once the technology has reached maturity. Finally step 6 identifies external developments impacting the technology as well as contributing uncertainties. A case study of a fuel cell-based propulsion system for a hydrogen-powered aircraft in 2040 illustrates the applicability of the framework. This study introduces a structured flowchart to support decision making in cases when parameter uncertainty should be integrated into pLCI modeling. By supporting the selection of appropriate prospective meth‑ ods as well as uncertainty identification and characterization strategies the proposed flowchart enhances the trans‑ parency consistency and representativeness of the pLCA results facilitating their broader application in emerging technology assessment methods.

This study conducts a Life Cycle Sustainability Assessment (LCSA) of hydrogen production pathways in Alberta Canada evaluating environmental economic and social dimensions. Eight pathways are analyzed: steam methane reforming (SMR) with and without carbon capture and storage (CCS) autothermal reforming (ATR) with and without CCS and with and without grid electricity as well as alkaline electrolysis using grid and wind electricity. While alkaline electrolysis with wind electricity shows the best performance under the climate change and ozone depletion categories ATR + CCS (CO2 capture rate of 91 % no-grid electricity) demonstrates the strongest performance in seven of nine environmental impact categories being the worst performer in none and having the lowest social risks. Economically SMR and ATR without CCS exhibit the lowest levelized cost of hydrogen followed by ATR + CCS (CO2 capture rate of 91 % no-grid electricity). ATR + CCS (CO2 capture rate of 91 % no-grid electricity) emerges as a promising pathway offering an overall balance of sustainability under the current study’s assumptions. The results suggest that a blue hydrogen to electricity scenario where ATR + CCS with 100 % on-site hydrogen-fueled power generation replaces grid electricity may be the most suitable pathway for hydrogen production in Alberta. Key recommendations include optimizing environmental performance in climate change and ozone depletion impacts reducing costs and mitigating social risks in ATR pathways. This LCSA supports policies and investments to advance hydrogen’s role in Alberta’s decarbonization and energy transition.

Addressing GHG emissions in industrial sectors is crucial for developed nations’ energy and environmental policies. European countries use diverse strategies to mitigate industrial GHG impacts with energy models evaluating national objectives and supporting policy implementation. A new hybrid bottom-up technology-oriented simulation model has been developed for Slovenia’s industrial sector focusing on energy-intensive industries like paper metal chemical and cement production. This model linked with the macroeconomic GEM model assesses the impacts of GHG reduction measures on the national economy. This paper introduces the Reference Energy System model for the industrial sector REES SLO aiding Slovenia’s NECP update. It details input parameters model structure proposed measures peculiarities of energy-intensive industries and calculation results. The findings indicate that decarbonizing Slovenia’s industrial sector is feasible but demands immediate policy intervention substantial investments and a collaborative approach among stakeholders. Advanced technologies such as carbon capture utilization and storage (CCUS) hydrogen-based solutions and enhanced energy efficiency measures are essential components of this transition. The integration of renewable energy sources (RES) and circular economy principles further strengthens pathways toward sustainability. The REES IND model underscores the importance of aligning industrial decarbonization strategies with broader economic and environmental objectives. It provides a comprehensive framework for policymakers to evaluate the effectiveness of proposed measures and their long-term impacts. Achieving these goals requires a phased approach beginning with energy efficiency improvements and progressing to structural changes and advanced technologies. The model’s insights pave the way for sustainable industrial transformation aligning Slovenia’s industrial sector with national and European Union climate objectives.

Differential diffusion (DD) and non-unity Lewis number (Le) effects in the filtered equations of the mixture fraction progress variable their respective sub-grid scale (SGS) variances and enthalpy are investigated using a priori and a posteriori analyses of a lifted turbulent hydrogen jet flame. The a priori analyses show that the absolute magnitudes of the DD terms in the filtered mixture fraction equation and its SGS variance are significant individually but their net contribution is small. The DD effects are found to be small for the progress variable and its SGS variance. One non-unity Le term is of similar magnitude to the turbulent flux for the filtered enthalpy and is independent of turbulent transport. Therefore a simple model for this effect is constructed using flamelets. A priori validation of this model is performed using direct numerical simulation data of a lifted hydrogen flame and its a posteriori verification is undertaken through two large eddy simulations. This effect influences the enthalpy field and hence the temperature is affected because of the relative increase (decrease) in thermal diffusivity for lean (rich) mixtures. Hence higher peak temperatures are observed in the rich mixture when the non-unity Le effects are included. However its overall effects on the flame lift-off height and flame-brush structure are observed to be small when compared with measurements. Hence the DD and non-unity Le effects are negligible for LES of partially premixed combustion of hydrogen–air mixtures in high Reynolds number flows. Novelty and significance The relative importance of differential and preferential diffusion effects for large eddy simulations using the tabulated chemistry approach is systematically assessed. The consistency among the complete set of equations and their closure models of the controlling variables (filtered mixture fraction progress variable their subgrid scale variances and enthalpy) for partially premixed combustion is maintained on the physical and mathematical grounds for the first time. The novelty of this work lies in the development validation and verification of a computationally simple yet accurate and robust model for these diffusion effects and its a priori and a posteriori analyses. It is demonstrated that the influence of non-equidiffusion is small for turbulent partially premixed hydrogen–air flames and hence the standard unity Lewis number approach is shown to be sufficient for turbulent partially premixed flames with high turbulence levels which are typical in practical applications.

This study examined the effects of microstructural alterations by controlling the surface carbon gradient via a thermal decarburizing process on hydrogen evolution adsorption and permeation along with neutral aqueous corrosion behavior of an ultra-high-strength steel with a tensile strength of 2.4 GPa. Microstructural analyses showed that an optimized decarburizing process at 1100 ◦C led to partial transformation to ferrite without precipitating Fe3C in a marked fraction. Electrochemical impedance spectroscopy along with the permeation results revealed that there was a notable decrease in hydrogen evolution and subsurface hydrogen concentration. Moreover immersion test in a neutral aqueous condition showed slower corrosion kinetics with a comparatively uniform corroded surface indicating improved corrosion resistance. However the extent of improvement is significantly limited under non-optimized decarburizing conditions specifically when the temperature is below or above 1100 ◦C due to insufficient decarburization or the formation of coarse-spheroidized Fe3C particles accompanied by a porous subsurface layer. In particular a far greater adsorption tendency at bridge sites on Fe3C (001) in a pre-charged surface is highlighted. This study provides insight that the adjustment of the carbon gradient through an optimized annealing process can be an effective technical strategy to overcome the critical drawbacks of ultrastrong martensitic steels under hydrogen-rich or corrosive conditions.

This review critically examines recent advancements in MXene-based nanocomposites and their roles in photocatalytic applications for environmental remediation and renewable energy. MXenes two-dimensional transition metal carbides nitrides and carbonitrides (Mn+1XnTx where M = transition metal X = C/N Tx = surface terminations such as –O –OH –F) exhibit high electrical conductivity tunable band structures hydrophilic surfaces and large specific surface areas. These properties make them highly effective in enhancing photocatalytic activity when incorporated into composite systems. The review summarizes synthesis methods structural modifications and the mechanisms underlying photocatalytic performance highlighting their efficiency in degrading organic inorganic and microbial pollutants converting CO₂ into value-added chemicals and generating H₂ via water splitting. Key challenges including stability oxidation and scalability are analyzed along with strategies such as surface passivation heterojunction formation and hybridization with antioxidant materials to improve performance. Future research should focus on developing green synthesis methods improving long-term stability and exploring scalable production to facilitate practical deployment. These insights provide a comprehensive understanding of MXene nanocomposites supporting their advancement as multifunctional photocatalysts for a clean and sustainable energy future.

Sustainable aviation fuel (SAF) derived from renewable resources presents a practical alternative to Jet-A fuel by mitigating the ecological impact of aviation’s reliance on fossil fuel. Among the available feedstocks waste biomass and waste oils present key advantages due to their abundance sustainability potential and waste valorization benefits. Despite continuous progress in SAF technologies comprehensive assessments of catalytic routes and their efficiency in transforming waste-based feedstocks into aviation-grade fuels remain limited. This review addresses this gap by systematically evaluating recent studies (2019–2024) that investigate catalytic conversion and upgrading of waste-derived biomass toward SAF production. Selection of thermochemical processes including pyrolysis gasification and hydrothermal liquefaction or biological pathways is driven by the physicochemical characteristics of the waste. These processes yield intermediates such as biocrude and bio-oils undergo catalytic upgrading to meet aviation fuel standards. Zeolitic acids sulfided NiMo or CoMo catalysts noble-metal/oxide systems and bifunctional or carbon-based catalysts drive hydroprocessing deoxygenation cracking and isomerisation reactions delivering high selectivity toward C8-C16fractions. Performance mechanisms and selectivity of these catalysts are critically assessed in relation to feedstock characteristics and operating conditions. Key factors such as metal-acid balance hierarchical porosity and tolerance to heteroatoms enhance catalytic efficiency. Persistent challenges including deactivation coking sintering and feedstock impurities continue to limit long-term performance and scalability in waste-to-SAF applications. Mitigation strategies including oxidative and resulfidation regeneration and support modification have demonstrated improved stability. Moreover waste-derived catalysts and circularity enhance process sustainability. Future work should align catalyst design with feedstock pretreatment and techno-economic assessments to scale sustainable and cost-effective waste-to-SAF pathways.

Achieving transport decarbonization depends on electric vehicle (EV) and fuel cell vehicle (FCV) deployment yet their material demands and impacts vary by vehicle type. This study explores how powertrain preferences in light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) shape future resource use and material-related environmental outcomes. Using dynamic material flow analysis and prospective life cycle assessment we assess three scenarios. In the S3 EV-dominant scenario 2050 lithium and cobalt demand rises by up to 11.9-fold and 1.8-fold relative to 2020 with higher global warming and human toxicity impacts. The S2 FCV-dominant scenario leads to a 21.7-fold increase in platinum-group metal demand driving up freshwater ecotoxicity and particulate emissions. A balanced S1 scenario EVs in LDVs and FCVs in HDVs yields moderate material demand and environmental burdens. These findings demonstrate that no single pathway can fully resolve material-related impacts while combining EVs and FCVs across LDVs and HDVs enables a more balanced and sustainable transition.

Financial viability is fundamental for investment success however long run sustainable investment relies on delivering tangible socio-economic benefits that foster societal acceptance enhancing community welfare and well-being. This study developed a quantitative model to evaluate the socio-economic impact of a proposed 1 GW green and 2 GW blue hydrogen investment in Tees Valley UK from 2027 to 2035. We introduced the socioeconomic impact (SEI) ratio defined as the ratio of socio-economic impact to the Levelized Cost of Hydrogen (LCOH) to illustrate the significance of socio-economic impact beyond financial returns. Findings indicate that the cumulative environmental and economic impact of green hydrogen amounted to £1.5 ± 0.5 bn and £1.35 ± 0.27 bn respectively with an employment impact of £269 ± 28 mn. In contrast the proposed blue hydrogen investment is expected to deliver £2.9 ± 0.9 bn environmental impact £1.84 ± 0.37 bn economic impact and £212 ± 26 mn employment social impact. The SEI ratio of green hydrogen was found to range between 48 % and 62 % and 60 %–79 % for blue hydrogen suggesting overall SEI ratio of approximately 60 % for combined green and blue investment. Sensitivity analysis using Monte Carlo simulation revealed that the results are particularly sensitive to the Gross Value Added (GVA) emission and employment factors. These findings highlight the importance of integrating socio-economic considerations into hydrogen planning investment strategies and decision-making to optimise environmental societal and economic outcomes.

This study presents an experimental approach to modelling PEM electrolysers for green hydrogen production using solar energy. The objective is to implement a temperature steady-state electrolyser model to assess the optimal coupling configuration with a photovoltaic plant and estimate the yearly hydrogen production capacity. The research focuses on the energy consumption of ancillary systems under different load conditions developing a steady-state operational model that improves hydrogen production predictions by accounting for these consumptions. The model based on polynomial equations captures the non-linear variation in energy costs under partial load conditions. PEM electrolysers produce hydrogen above 3.0 quality (99.9% purity) and it is feasible to integrate purification processes to reach 5.0 quality (99.999% purity). While small-scale systems include purification large-scale facilities separate it enabling process optimisation. Two models are introduced to estimate hydrogen mass flow depending on purity: a base-purity model and a high-purity model that includes drying and pressure swing adsorption. Both are based on experimental data from a five-year-old small-scale electrolyser and are applicable to large-scale systems at partial load. Due to test conditions the model applied to large-scale facilities underestimates hydrogen production affected by energy losses from a non-optimised purification process and electrolyser degradation. Model validation with large-scale operational data from the literature shows the model captures plant behaviour well despite the consistent underestimation described above. The model is applied to several European locations to identify optimal photovoltaic-to-electrolyser ratios. Oversizing factors between 1.4 and 2 are needed to cover ancillary consumption. The levelised cost remains comparable for both purity levels despite higher energy demands for high-purity hydrogen due to the greater cost of the electrolyser over the photovoltaic plant.

This study aims to qualitatively and quantitatively assess the ability of the flow solver “reactingFoam” of the open-source OpenFOAM software v.2506 for a control-volume-based computational fluid dynamics (CFD) solver in treating the reacting flow problem of a popular benchmarking bluff-body-stabilized turbulent diffusion (non-premixed) flame that is the HM1 flame. The HM1 flame has a fuel stream composed of 50% hydrogen (H2) and 50% methane (CH4) by mole. Thus the acronym “HM1” stands for “hydrogen– methane with level 1 of jet speed”. This fuel stream is surrounded by a coflow of oxidizing air jet. This flame was studied experimentally at the University of Sydney. A measurement dataset of flow and chemical fields was compiled and made available freely for validating relevant computational models. We simulate the HM1 flame using the reactingFoam solver and report here various comparisons between the simulation results and the experimental results to aid in judging the feasibility of this open-source CFD solver. The computational modeling was conducted using the specialized wedge geometry suitable for axisymmetric problems. The turbulence–chemistry interaction (TCI) was based on the Chalmers’ partially stirred reactor (CPaSR) model. The two-equation k-epsilon framework is used in modeling the small eddy scales. The four-step Jones-Lindstedt (JL) reaction mechanism is used to describe the chemical kinetics. Two meshes (coarse and fine) were attempted and a converged (mesh-independent) solution was nearly attained. Overall we notice good agreement with the experimental data in terms of resolved profiles of the axial velocity mass fractions and temperature. For either mesh resolution the overall deviation between the computational results and the experimental results is approximately 8% (mean absolute deviation) and 10% (root mean square deviation). These are favorably low. The current study and the presented details about the reactingFoam solver and its implementation can be viewed as a good case study in CFD modeling of reacting flows. In addition the information we provide about the measurement dataset the emphasized recirculation zone the entrainment phenomena and the irregularity in the radial velocity can help other researchers who may use the same HM1 data.

The decarbonization of regional passenger rail transport is one of the key challenges for the sustainable transformation of the transport sector in Poland. While railway transportation remains one of the least carbon-intensive modes of transport significant emission disparities persist between electrified and non-electrified lines where diesel traction is still prevalent. This article presents a comparative analysis of various propulsion technologies—diesel hybrid battery-electric and hydrogen fuel-cell—taking into account both local (TTW) and total (WTW) greenhouse gas emissions. The study incorporates Poland’s current energy mix and proposes a methodological framework to assess emissions at the line level. It highlights the risks of focusing exclusively on in situ zero-emission technologies and calls for a more flexible efficiency-based approach to fleet modernization. The analysis demonstrates that hybrid and optimized combustion-based systems can provide substantial emission reductions in the short term especially in rural and transitional regions. The paper also critically discusses transport funding policies pointing to discrepancies between incentives for private electric mobility and the lack of support for public transport solutions that could effectively counter mobility exclusion. The presented methodology and conclusions provide a basis for further research on transport decarbonization strategies tailored to national and regional contexts.

The maritime industry is under increasing pressure to reduce greenhouse gas emissions especially in countries such as Saudi Arabia that are actively working to transition to cleaner energy. In this paper a new hybrid shipboard power system which incorporates wind turbines solar photovoltaic (PV) panels proton-exchange membrane fuel cells (PEMFCs) and a battery energy storage system (BESS) together for propulsion and hotel load services is proposed. A multi-loop Energy Management System (EMS) based on proportional–integral control (PI) is developed to coordinate the interconnections of the power sources in real time. In contrast to the widely reported model predictive or artificial intelligence optimization schemes the PI-derived EMS achieves similar power stability and hydrogen utilization efficiency with significantly reduced computational overhead and full marine suitability. By taking advantage of the high solar irradiance and coastal wind resources in Saudi Arabia the proposed configuration provides continuous near-zeroemission operation. Simulation results show that the PEMFC accounts for about 90% of the total energy demand the BESS (±0.4 MW 2 MWh) accounts for about 3% and the stationary renewables account for about 7% which reduces the demand for hydro-gas to about 160 kg. The DC-bus voltage is kept within ±5% of its nominal value of 750 V and the battery state of charge (SOC) is kept within 20% to 80%. Sensitivity analyses show that by varying renewable input by ±20% diesel consumption is ±5%. These results demonstrate the system’s ability to meet International Maritime Organization (IMO) emission targets by delivering stable near-zero-emission operation while achieving high hydrogen efficiency and grid stability with minimal computational cost. Consequently the proposed system presents a realistic certifiable and regionally optimized roadmap for next-generation hybrid PEMFC–battery–renewable marine power systems in Saudi Arabian coastal operations.

Ammonia is a highly promising zero-carbon fuel for engines. However it exhibits high ignition energy slow flame propagation and severe pollutant emissions so it is usually burned in combination with highly reactive fuels such as hydrogen. An accurate understanding and modeling of ammonia–hydrogen combustion is of fundamental and practical significance to its application. Deep Neural Networks (DNNs) demonstrate significant potential in autonomously learning the interactions between high-dimensional inputs. This study proposed a deep neural network-based method for optimizing chemical reaction mechanism parameters producing an optimized mechanism file as the final output. The novelty lies in two aspects: first it systematically compares three DNN structures (Multilayer perceptron (MLP) Convolutional Neural Network and Residual Regression Neural Network (ResNet)) with other machine learning models (generalized linear regression (GLR) support vector machine (SVM) random forest (RF)) to identify the most effective structure for mapping combustion-related variables; second it develops a ResNet-based surrogate model for ammonia–hydrogen mechanism optimization. For the test set (20% of the total dataset) the ResNet outperformed all other ML models and empirical correlations achieving a coefficient of determination (R2 ) of 0.9923 and root mean square error (RMSE) of 135. The surrogate model uses the trained ResNet to optimize mechanism parameters based on a Stagni mechanism by mapping the initial conditions to experimental IDT. The results show that the optimized mechanism improves the prediction accuracy on laminar flame speed (LFS) by approximately 36.6% compared to the original mechanism. This method while initially applied to the optimization of an ammonia–hydrogen combustion mechanism can potentially be adapted to optimize mechanisms for other fuels.

Green hydrogen is essential for advancing the energy transition as it is regarded as a CO2-neutral flexible and storable energy carrier. Particularly in steel production which is known for its high energy intensity hydrogen has great potential to replace conventional energy sources. In a game-theoretic bi-level optimization model involving a power plant operator and a steel company we investigate in which situations the production and use of green hydrogen is advantageous from an economic and ecological point of view. Through an extensive case study based on a realworld scenario we can observe that hydrogen production can serve as a profitable and flexible secondary income opportunity for the power plant operator and help avoid curtailment and spot market losses. On the other hand the steel manufacturer can reduce CO2 emissions and associated costs while also meeting the growing customer demand for low-carbon products. However our findings also highlight important trade-offs and uncertainties. While lower electricity generation costs or improved electrolyzer efficiency enhance hydrogen’s competitiveness increases in coal and CO2 emission prices do not always result in greater hydrogen adoption. This is due to the persistent reliance on a non-replaceable share of coal in steel production which raises the overall cost of both low-carbon and carbon-intensive steel. The model further shows that consumer demand elasticity plays a critical role in determining hydrogen uptake. These insights underscore the importance of not only reducing hydrogen costs but also designing supportive policies that address market acceptance and the full cost structure of green industrial products.

A comprehensive understanding of consumer preferences and demand factors is essential for successfully implementing demand-side strategies for alternative energy solutions such as hydrogen. This study aims to identify the key determinants influencing the adoption propensity for Hydrogen fuel cell vehicles (HFCVs) in the Kingdom of Saudi Arabia (KSA). Developing a conceptual framework to organise the key factors influencing consumers’ decisions to adopt or reject this technology. Using data from an online survey of 384 prospective customers we employed structural equation modelling (SEM) via Smart-PLS 4.1 to analyze consumer intent. The findings reveal that perceived benefits barriers opinions and governmental initiatives have a significant impact on the likelihood of HFCV adoption. The study emphasises the significance of collaborative efforts among key stakeholders including manufacturers hydrogen producers research institutions and financial entities in addressing challenges and advancing the development of the hydrogen transportation ecosystem in KSA. Financial incentives and subsidies such as purchasing subsidies awareness and reduced registration costs for HFCVs may be instituted.

With the growing significance of hydrogen in the global energy transition research on its pricing mechanisms has become increasingly crucial. Focusing on hydrogen markets predominantly supplied by electrolytic production this study proposes a nodal marginal hydrogen price decomposition algorithm that explicitly incorporates the time-delay dynamics inherent in hydrogen transmission. A four-dimensional price formation framework is established comprising the energy component network loss component congestion component and time-delay component. To address the nonconvex optimization challenges arising in the market-clearing model an improved second-order cone programming method is introduced. This method effectively reduces computational complexity through the reconstruction of time-coupled constraints and reformulation of the Weymouth equation. On this basis the analytical expression of the nodal marginal hydrogen price is rigorously derived elucidating how transmission dynamics influence each price component. Empirical studies using a modified Belgian 20-node system demonstrate that the proposed pricing mechanism dynamically adapts to load variations with hydrogen prices exhibiting a strong correlation with electricity cost fluctuations. The results validate the efficacy and superiority of the proposed approach in hydrogen energy market applications. This study provides a theoretical foundation for designing efficient and transparent pricing mechanisms in emerging hydrogen markets.

The operational optimization of industrial boilers utilizing hydrogen-enriched natural gas is constrained by two critical gaps: insufficient understanding of the coupled effects of hydrogen blending ratio equivalence ratio and boiler load on combustion performance— compounded by unresolved challenges of combustion instability flashback and elevated NOx emissions—and a lack of systematic investigations combining these parameters in industrial-scale systems (prior studies often focus on single variables like hydrogen fraction). To address this a comprehensive computational fluid dynamics (CFD) analysis was conducted on a 2.1 MW industrial boiler employing the Steady Laminar Flamelet Model (SLFM) with a modified k-ε turbulence model and the GRI-Mech 3.0 mechanism. Simulations covered hydrogen fractions (f(H2) = 0–25%) equivalence ratios (Φ = 0.8–1.2) and load conditions (15–100%). All NOx emissions reported herein are normalized to 3.5% O2 (mg/Nm3 ) for regulatory comparison. Results show that increasing the hydrogen content raises the flame temperature and NOx emissions while reducing CO and unburned hydrocarbons; a higher equivalence ratio elevates temperature and NOx with Φ = 0.8 balancing efficiency and emission control; and reducing load significantly lowers furnace temperature and NO emissions. Notably the boiler’s unique staged-combustion configuration (81% fuel supply to the central rich-combustion nozzle 19% to the concentric lean-combustion nozzle) was found to mitigate NOx formation by 15–20% compared to single-inlet burner designs and its integrated cyclone blades (generating maximum swirling velocity of 14.2 m/s at full load) enhanced fuel–air mixing which became particularly critical for maintaining combustion stability at low loads (≤20%) and high hydrogen blending ratios (≥20%). This study provides quantitative trade-off insights between combustion efficiency and pollutant formation offering actionable guidance for the safe efficient operation of hydrogen-enriched natural gas in industrial boilers.

This study investigates the combustion process in a marine spark-ignition engine fueled with an ammonia–hydrogen blend (15% hydrogen by volume) using a passive pre-chamber. A 3D-CFD model supported by a 1D engine model was employed to analyze equivalence ratios between 0.7 and 0.9 and pre-chamber nozzle diameters from 7 to 3 mm. Results indicate that combustion is consistently initiated by turbulent jets but at an equivalence ratio of 0.7 the charge combustion is incomplete. For lean mixtures reducing nozzle size improves flame propagation although not sufficiently to ensure stable operation. At an equivalence ratio of 0.8 reducing the nozzle diameter from 7 to 5 mm advances CA50 by about 6 CAD while further reduction causes minor variations. At richer conditions nozzle diameter plays a negligible role. Optimal performance was achieved with a 7 mm nozzle at equivalence ratio 0.8 delivering about 43% efficiency and 1.17 MW per cylinder.

The hydrogen energy industry is rapidly developing positioning hydrogen refueling stations (HRSs) as critical infrastructure for hydrogen fuel cell vehicles. Within these stations hydrogen compressors serve as the core equipment whose performance and reliability directly determine the overall system’s economy and safety. This article systematically reviews the working principles structural features and application status of mechanical hydrogen compressors with a focus on three prominent types based on reciprocating motion principles: the diaphragm compressor the hydraulically driven piston compressor and the ionic liquid compressor. The study provides a detailed analysis of performance bottlenecks material challenges thermal management issues and volumetric efficiency loss mechanisms for each compressor type. Furthermore it summarizes recent technical optimizations and innovations. Finally the paper identifies current research gaps particularly in reliability hydrogen embrittlement and intelligent control under high-temperature and high-pressure conditions. It also proposes future technology development pathways and standardization recommendations aiming to serve as a reference for further R&D and the industrialization of hydrogen compression technology.

The gradual exhaustion of fossil fuel reserves along with the adverse effects of their consumption on global climate drives the need for research into alternative energy sources that can meet the growing demand in a sustainable and eco-friendly way. Among these hydrogen stands out as one of the most promising options for the automotive sector being the cleanest available fuel and capable of being produced from renewable resources. This paper reviews the existing literature on compression ignition engines operating in a dualfuel configuration where diesel serves as the ignition source and hydrogen is used to enhance the combustion process. The reviewed studies focus on engine systems with hydrogen injection into the intake manifold. The investigations analyzed the influence of hydrogen energy fraction on combustion characteristics engine performance combustion stability and exhaust emissions in diesel/hydrogen dual-fuel engines operating under full or near-full-load conditions. The paper identifies the main challenges hindering the widespread and commercial application of hydrogen in diesel/hydrogen dual-fuel engines and discusses potential methods to overcome the existing barriers in this area.

Fuel cells are highly efficient electrochemical devices that convert the chemical energy of fuel directly into electrical energy while generating minimal pollutant emissions. In recent decades they have established themselves as a key technology for sustainable energy supply in the transport sector stationary systems and portable applications. In order to assess their real contribution to environmental protection and energy efficiency a comprehensive analysis of their life cycle Life Cycle Assessment (LCA) is necessary covering all stages from the extraction of raw materials and the production of components through operation and maintenance to decommissioning and recycling. Particular attention is paid to the environmental challenges associated with the extraction of platinum catalysts the production of membranes and waste management. Economic aspects such as capital costs the price of hydrogen and maintenance costs also have a significant impact on their widespread implementation. This manuscript presents detailed mathematical models that describe the electrochemical characteristics energy and mass balances degradation dynamics and cost structures over the life cycle of fuel cells. The models focus on proton exchange membrane fuel cells (PEMFCs) with possible extensions to other types. LCA is applied to quantify environmental impacts such as global warming potential (GWP) while the levelized cost of electricity (LCOE) is used to assess economic viability. Particular attention is paid to the sustainability challenges of platinum catalyst extraction membrane production and end-of-life material recovery. By integrating technical environmental and economic modeling the paper provides a systematic perspective for optimizing fuel cell deployment within a circular economy.

Integrated Energy Systems (IESs) which leverage the synergistic coordination of electricity heat and gas networks serve as crucial enablers for a low-carbon transition. Current research predominantly treats energy storage as a subordinate resource in dispatch schemes failing to simultaneously optimise IES economic efficiency and storage operators’ profit maximisation thereby overlooking their potential value as independent market entities. To address these limitations this study establishes an operator-autonomous management framework incorporating electrical thermal and hydrogen storage in IESs. We propose a joint optimal dispatch model for hybrid energy storage systems in low-carbon IES operation. The upper-level model minimises total system operation costs for IES operators while the lower-level model maximises net profits for independent storage operators managing various storage assets. These two levels are interconnected through power price and carbon signals. The effectiveness of the proposed model is verified by setting up multiple scenarios for example analysis.

The effect of tempering temperature and tempering time on the density of hydrogen traps hydrogen diffusivity and microhardness in a vanadium-modified AISI 4140 martensitic steel was determined. Tempering parameters were selected to activate the second third and fourth tempering stages. These conditions were intended to promote specific microstructural transformations. Permeability tests were performed using the electrochemical method developed by Devanathan and Stachurski and microhardness was measured before and after these tests. It was observed that hydrogen diffusivity is inversely proportional to microhardness while the density of hydrogen traps is directly proportional to microhardness. The lowest hydrogen diffusivity the highest trap density and the highest microhardness were obtained in the as-quenched condition and the tempering at 286 ◦C for 0.25 h. In contrast tempering at a temperature corresponding to the fourth tempering stage increases hydrogen diffusivity and decreases the density of hydrogen traps and microhardness. However as the tempering time or temperature increases the opposite occurs which is attributed to the formation of alloy carbides. Finally hydrogen has a softening effect for tempering temperatures corresponding to the fourth tempering stage tempering times of 0.25 h and in the as-quenched condition. However with increasing tempering time hydrogen has a hardening effect.

The growing demand for green hydrogen is driving the expansion of water electrolysis. The resulting oxygen byproduct offers potential added value when used in sectors with high oxygen demand such as wastewater treatment. This study investigates the techno-economic viability of using electrolysis oxygen to supplement conventional air blowers in the aeration process of municipal wastewater treatment plants (WWTPs) to reduce aeration costs and thereby improve the overall economics of hydrogen production. A comprehensive system model is developed incorporating renewable electricity supply water electrolysis hydrogen compression storage and transport as well as WWTP aeration via conventional air blowers and electrolysis oxygen. Results show that electrolysis oxygen can reduce WWTP aeration costs by up to 68%. If these cost reductions are attributed as a benefit to the hydrogen system they correspond to hydrogen supply cost savings of up to 0.39 EUR/kgH2. However the analysis indicates that economic viability is substantially influenced by factors such as the distance of hydrogen transport from the WWTP to the European Hydrogen Backbone feed-in point which should not exceed 25 km and the alignment between the scale of hydrogen production and the size of the WWTP with cost-effective integration being particularly feasible for larger WWTPs (≥500000 PE).

Hybrid renewable energy systems (HRESs) are an effective tool for addressing the challenges of rural electrification in sub-Saharan Africa (SSA). However their viability is limited by the lifespan environmental impacts high costs and inefficiency of conventional energy storage technologies (battery and pumped-hydro). This study examines a hydrogen-based energy storage system combined with photovoltaic (PV) and wind energy for the electrification of Dargalla a village in northern Cameroon. The goal is to meet community and agricultural electricity needs while optimizing the system. The analysis utilized HOMER software to simulate model and optimize the system. The optimal architecture consisted of a 50-kW photovoltaic (PV) array a 10-kW wind turbine a 10-kW fuel cell a 30-kW electrolyser a 25-kg hydrogen tank and a 10-kW converter. The optimised system’s net present cost and cost of energy were assessed at USD 138202 and USD 0.443/kWh respectively. Sensitivity analysis results showed that areas with high wind speeds would be mainly suitable for the proposed system. Moreover with the upcoming decrease in the costs of fuel cells and PV components such systems are expected to become more economically viable in the future leading to the conclusion that integration of hydrogen-based energy storage technology in HRESs in SSA can effectively address the United Nations Sustainable Development Goals (UNSDG) and the historic Paris Climate Agreement (HCA).

In order to assess the decarbonization potential and overall environmental benefits of new reduction pathways in the ironmaking industry using hydrogen to produce Direct Reduced Iron (DRI) a coupled approach combining process simulation for rigorous technical and energy evaluation of iron ore conversion and Life Cycle Assessment (LCA) for environmental assessment was developed and extended to two alternative renewable heating strategies: (i) electric gas heating and (ii) solar reactor heating. The entire hydrogen-based ironmaking process including conversion in a shaft reactor gas and solid heating gas recycling and electrolysis was therefore simulated. The hydrogen-based reduction of iron ores in the shaft reactor was modeled using a rigorous reactor model describing the reduction of multi-layer iron ore pellets in countercurrent gas–solid moving beds with the particularity of representing the dual influence of particle size and temperature on conversion. The remainder of the process including gas recycling and hydrogen production was simulated using ProSim software. The hydrogen-based green ironmaking scenarios were then compared to MIDREX NG a leading natural gas-based reduction technology. Hydrogen-based scenarios powered by the French electricity mix reduce carbon footprints by 53 % for electric gas heating and 57 % for solar reactor heating potentially reaching 82 % (− 0.79 kgCO2-eq/kgDRI) with low-carbon electricity (hydro nuclear). Compared to MIDREX NG the energy requirements of both hydrogen-based scenarios are primarily determined by the use of electricity for hydrogen production illustrating the importance of hydrogen production for the assessment of future hydrogen-based green ironmaking.

Developing green hydrogen energy can alleviate the problem of CO2 emissions caused by excessive use of fossil fuels. In-situ capture of CO2 for enhanced H2 production in zero-carbon energy biomass-H2O gasification can achieve the dual effects of green H2 production and negative carbon. The study used red mud (RM) to modify CaO and prepare dual-functional materials (DFMs). And the in-situ CO2 capture enhanced H2 production and regeneration cycle performance of DFMs in biomass-H2O gasification were studied and the influence of biomass ash on the H2 production and low-temperature (650 ◦C) regeneration performance of DFMs in the cycle was analyzed. The results are as follows: In DFMs catalyzed biomass-H2O gasification due to the continuous deposition of alkali and alkaline earth metals (AAEMs) in biomass ash with increasing cycle times its catalytic effect increased H2 production by 27 % after twenty cycles and the pore structure degradation and cycle stability of DFMs decreased by 44.71 %. DFMs have demonstrated excellent catalytic performance and cycling stability in the catalytic removal of ash from biomass. After twenty cycles the production of H2 only decreased by 20.59 % and the performance of CaO decreased by 26.67 % demonstrating the enormous potential of DFMs for in-situ CO2 capture and enhanced H2 production.

Climate-change mitigation in North America demands rapid deep cuts in carbon-dioxide emissions from hard-toabate industrial power-generation and transport sectors. Carbon capture and storage (CCS) is one of the few technological routes that can decouple continued use of fossil-derived energy and materials from their climate externalities. Yet deployment across the US and Canada still trails the scale implied by regional net-zero pledges. This review addresses that gap by synthesizing technical economic policy and social dimensions of CCS and complements global syntheses with a granular assessment of North America’s unique emission profile infrastructure advantages and regulatory frameworks. Methodologically the review disaggregates the CCS chain into six pillars: (i) current emission baselines; (ii) capture systems icluding post- pre- and oxy-combustion chemical-looping combustion (CLC) and direct air capture (DAC); (iii) capture technologies (e.g. absorption adsorption membrane cryogenic and hybrid processes); (iv) storage pathways (geological oceanic and emerging biological or mineral options); (v) cross-cutting economic policy and social factors; and (vi) deployment status plus future outlook. Post-combustion capture remains the most retrofit-ready option for the region’s ageing coal and gas fleet yet solvent regeneration still imposes energy penalties of 8–10 percentagepoints. Pre-combustion and oxy-fuel routes offer thermodynamic advantages for new-build plants but require high-capex gasifiers or cryogenic air separation units slowing adoption. Emerging CLC and DAC concepts could unlock low-carbon fuels and negative emissions respectively but remain costly and pre-commercial. No single technology meets all performance criteria making hybrid configurations—such as membrane–cryogenic or membrane–amine schemes—particularly promising. North America’s subsurface offers multi-teratonne theoretical storage capacity in saline formations depleted hydrocarbon reservoirs and CO2-EOR sites suggesting physical room is not the bottleneck. Instead economics dominate: levelized capture costs today range from around $15/tCO2 in natural-gas processing to over $120/t in power and cement and long-distance pipeline networks are sparse outside existing enhanced oil recovery (EOR) corridors. Recent federal incentives can shift project economics decisively yet policy volatility and permitting hurdles still threaten investment certainty. Societal acceptance emerges as another critical lever. Surveys reveal generally favorable attitudes toward CCS in principle but heightened opposition to local storage projects. Transparent monitoring–verification frameworks benefit-sharing mechanisms and durable bipartisan policies are therefore essential to secure a “social licence” for large-scale CO2 injection. This review concludes that widescale CCS in North America is technically feasible and increasingly cost-competitive when paired with robust incentives abundant storage capacity and existing pipeline know-how. Realizing its full mitigation potential will hinge on coordinated build-out of transport networks harmonized federal–provincial regulations continued R&D into low-energy capture materials and integrated assessments that weigh CCS alongside renewables efficiency and negative-emission strategies. The roadmap presented herein provides stakeholders with actionable insights to accelerate that transition positioning North America as both a proving ground and a global exemplar for scalable responsibly governed CCS.

The management of sewage sludge presents a pressing environmental and economic challenge due to its increasing global production and complex hazardous composition. Gasification offers a viable method for converting this waste into valuable energy resources. This study investigates whether integrating experimental and computational techniques can enhance the understanding and optimization of sludge gasification. Two types of sewage sludge SSG from Rethymno and SSD from Dubai were evaluated using an entrained flow gasifier under controlled thermal and flow conditions. The methodology combines equilibrium modeling computational fluid dynamics (CFD) drop tube reactor (DTR) experiments and artificial neural network (ANN) modeling. The ANN was combined with Kissinger analysis to obtain kinetics from the ANN outputs and derive thermodynamic parameters used to enhance CFD fidelity. Gas composition analysis and scanning electron microscopy (SEM) revealed that SSD decomposes more easily with a lower activation energy (42.29–138.31 kJ/mol) and a lower Gibbs free energy. In contrast SSG demonstrated greater thermal stability and reactivity. SSG achieved consistently higher cold gas efficiency (CGE) reaching 53.66 % in equilibrium modeling 45.50 % in CFD and 38.90 % in experiments compared to SSD’s 48.86 % 37.81 % and 31.19 % respectively. SEM imaging confirmed an increase in porosity and surface area for SSG after gasification. These results indicate that the type of sludge has a significant impact on energy recovery and that ANN-calibrated thermokinetics and CFD enhance process predictability. This integrated method scales hydrogen generation and promotes sustainable waste-toenergy technology.

Underground hydrogen storage (UHS) represents a large-scale energy storage system aiming to ensure a consistent supply by storing hydrogen generated from surplus energy. In the practice of UHS cushion gas is typically injected into the formation to maintain reservoir pressure for efficient hydrogen withdrawal. This paper reviews the impact of cushion gas on the performance of UHS from both experimental and numerical simulation perspectives. The thermophysical (e.g. density viscosity compressibility and solubility) and petrophysical (interfacial tension wettability and relative permeability) properties as well as the mixing and diffusion behavior of different cushion gases were compared. The corresponding impact of different cushion gases on plume migration and trapping potential is then discussed. Furthermore this review critically analyzes and explains the impact of various factors on the performance of UHS including the type of cushion gas the composition of cushion gas mixtures the volume of injected cushion gas and the effects of bio-methanation processes. The corresponding analysis specifically focuses on key performance indicators including H2 recovery factor formation pressure brine production and H2 outflow purity. Thus this review provides a comprehensive analysis of the role of cushion gas in UHS offering insight into the effective management and optimization of cushion gas injection in field-scale UHS operations.

This study investigates the potential of green hydrogen production from small and large-scale photovoltaic water electrolysis systems under tropical climate conditions with particular emphasis on the Levelized Cost of Hydrogen (LCOH) in Santo Domingo Dominican Republic. The hydrogen production system was developed using MATLAB/SIMULINK R2023b. The system simulation incorporates a commercial proton exchange membrane (PEM) electrolyzer driven by a DC/DC converter is also evaluated under varying environmental scenarios based on real meteorological data for temperature and solar irradiance. Dynamic simulations were performed to analyze the relationship between solar resource availability and hydrogen production. Results indicate that at small-scale 3.68 kWp PV + 0.017 kW PEM LCOH is 104.52 USD/kg for PV-only compared to 17.09 USD/kg for a grid sourced electricity case. At large-scale 100 MWp PV + 60 MWe PEM LCOH falls to 7.05 USD/kg under PVonly operation Utilization factor Uf = 0.31 and 3.61 USD/kg with grid supplied backup Uf = 0.85 illustrating the massive cost reduction achievable through economies of scale. Model validation showed a high degree of accuracy with an average percentage error of 1.41 % when comparing simulated and manufacturer provided parameters curves. A comparative carbon footprint analysis demonstrated the environmental advantages of PV driven hydrogen production over conventional fossil fuels methods. These findings are especially relevant for such climates and support the advancement of Sustainable Development Goals 7 and 13 positioning green hydrogen as a key vector for the clean energy transition.

The accelerating global demand for hydrogen is pushing for renewable and waste derived hydrogen production processes where date palm waste (DPW) has been identified as an available and unexploited agricultural residue that has the potential to be a sustainable source of hydrogen. The current work focuses on developing and evaluating four different process configurations in terms of energy environment and economics for producing hydrogen from DPW using Aspen Plus® simulation tool. Case 1 represents the standalone DPW gasification with CO₂ capture via methanol absorption Case 2 represents the DPW gasification with CaO-based chemical looping for CO₂ capture Case 3 represents the DPW gasification integrated with steam methane reforming (SMR) and methanol-based CO₂ capture and Case 4 represents the DPW gasification integrated with SMR and CaO-based CO₂ capture. Each case was evaluated in terms of syngas composition hydrogen production lower heating value CO₂ captured utility demand process efficiency and H2 production cost. Hydrogen production ranged from 974.55 t/year (Case 1) and 988.83 t/year (Case 2) to 2032.32 t/year (Case 3) and 2048.61 t/year (Case 4). CO₂ capture was also more effective in Case 4 (16929.49 t/year) compared to Case 1 (7676.30 t/year). Process efficiency improved from 33 % in Case 1 to 47 % in Case 2 and from 32 % in Case 3 to further to 55 % in Case 4. Economically Case 1 offered the highest hydrogen production cost ($5.03/kg) followed by Case 2 ($4.77/kg) while Case 3 and Case 4 achieved significantly lower production costs of $2.89/kg and $2.69/kg respectively.

This review explores the evolving role of hydrogen in global decarbonization analysing national hydrogen strategies value chain developments and future market potential. Through a comprehensive review of policy frameworks market trends and technology pathways the paper evaluates hydrogen’s role in decarbonising sectors such as steel ammonia methanol refining transport and power generation. The study highlights the expected growth in global hydrogen demand projected cost reductions and advancements in production technologies including electrolysis and carbon capture-integrated hydrogen production. While green hydrogen offers a sustainable pathway challenges remain in infrastructure development energy efficiency and the integration of hydrogen into existing energy networks. The paper considers the economic and technological factors affecting international hydrogen trade. Despite more than 30 national hydrogen strategies being in place significant challenges remain particularly in scaling renewable electricity and infrastructure to meet growing hydrogen demand projected to reach up to 600 Mt by 2050. Key players such as Australia Norway and the Middle East are positioning themselves as major hydrogen exporters by leveraging their abundant natural resources and strategic infrastructure. On the demand side countries like Japan South Korea Germany and the Netherlands are emerging as leading importers investing heavily in hydrogen hubs and import terminals to secure future energy supplies. The expansion of hydrogen storage and transportation alongside investments in large-scale hydrogen hubs will be critical for market growth. Additionally the study emphasize the need for policy alignment strategic investments and cross-border cooperation to accelerate hydrogen adoption. Hydrogen can become a key element of the global clean energy transition by addressing optimal energy consumption and by leveraging renewable resources.

Fuel cell electric vehicles (FCEVs) are zero-emission but face cost and power density challenges. To mitigate these limitations a novel 3D-ordered nano-structured self-supporting membrane electrode assembly (MEA) has been developed. This paper investigates the optimal component sizing of the battery and fuel cell in FCEVs equipped with 3D-ordered MEAs integrating the energy management. To explore the trade-offs between component cost operational cost and fuel cell degradation the sizing and energy management problem is formulated into a multi-objective optimisation problem. A Pareto frontier (PF) study is conducted using the decomposed multi-objective evolutionary algorithm (MOEA/D) for a more diverse distribution of feasible solutions. The modular design of fuel cells is derived from a scaled and stressed experiment. After executing MOEA/D across the three aggressive driving cycles power source configurations are selected from the corresponding PFs based on objective trade-offs ensuring robustness of the overall system. The optimisation performance of the MOEA/D is compared with that of the multi-objective Particle Swarm Optimisation. In addition the selected powertrain configurations are evaluated and compared through standard and realworld driving cycles in a simulation environment. This paper also performs a sensitivity analysis to reveal the influence of diverse component unit costs and hydrogen price. The results indicate that the mediumsized configuration consisting of a 63.31 kW fuel cell stack and a 52.15 kWh battery pack delivers the best overall performance. It achieves a 26.71% reduction in component cost and up to 12.76% savings in hydrogen consumption across various driving conditions. These findings provide valuable insights into the design and optimisation of fuel cell systems for FCEVs.

Coastal regions in Cameroon including Douala Kribi Campo Dibamba and Limbe faced persistent electricity challenges driven by grid instability growing demand and dependence on fossil fuels. Solar resource availability was high but intermittent whereas tidal energy was predictable and energy-dense yet underused. This pilot delivers the first Cameroonian assessment of an off-grid tidal/PV/electrolyzer/hydrogen-storage/fuel-cell architecture explicitly co-optimizing electricity service and green hydrogen production and evaluating performance with a tri-metric economic lens (net present cost levelized cost of electricity and the levelized cost of hydrogen). The system was optimized to minimize net present cost (NPC) levelized cost of electricity (LCOE) levelized cost of hydrogen (LCOH) and three tidal-flow scenarios were analyzed to represent hydrokinetic variability. The design served households small businesses fishing activities schools and health facilities with a baseline demand of 389.50 kWh/day; surplus renewable power drove the electrolyzer to produce hydrogen for later reconversion in the fuel cell. Under the first scenario (1.25 m/s average speed) the optimal mix comprised 137 PV modules (600 W each) a 100 kW fuel cell six 40 kW tidal turbines six 10 kW electrolyzers a 19.5 kW converter and 41 hydrogen tanks (40 L each) yielding an NPC of US$ 2.16 million an LCOE of US$ 0.782/kWh and a LCOH of US$ 19.2/kg of hydrogen. The second scenario (1.47 m/s) required only 12 PV modules one electrolyzer and an 11.3 kW converter lowering costs to an NPC of US$ 1.52 million an LCOE of US$ 0.553/ kWh and a LCOH of US$ 15.4/kg of hydrogen. In the third scenario (1.61 m/s) the configuration shifted to 298 PV modules three tidal turbines eight electrolyzers and a 39.6 kW converter resulting in the highest NPC (US$ 2.47 million) and LCOE (US$ 0.901/kWh) with a LCOH of US$ 18.8/kg of hydrogen. The study also contributes a transparent component-wise employment indicator linking installed capacities/energies to jobs; deployment is expected to create about seven local jobs during installation and early operation tidal turbines (3) solar panels (1) electrolyzers (1) hydrogen tanks (1) and fuel cell (1) with additional minor operation and maintenance positions thereafter. Social analysis indicated improved energy access support for local livelihoods and job creation; environmental results confirmed clean operation with limited marine disturbance. A sensitivity study varying capital and replacement-cost multipliers showed robust performance across economic conditions. Taken together these contributions provide a decision-ready blueprint for coastal communities: a first-of-its-kind Cameroonian hybrid that quantifies both electricity and hydrogen costs (including feasible LCOH) and demonstrates socio-economic co-benefits offering a cost-effective pathway to strengthen energy security foster local development and reduce environmental impact.

The adoption of clean hydrogen is expected to transform the global energy landscape reducing greenhouse gas emissions bridging gaps in renewable energy integration and driving innovation across multiple sectors. In the medical and pharmaceutical industries hydrogen offers unique opportunities for transformative progress. This review critically examines recent advances in three domains: hydrogen fuel cells as reliable scalable and sustainable energy solutions for hospitals; molecular hydrogen as a therapeutic and preventive medical gas particularly for brain disorders; and hydrogenation technologies for the efficient and sustainable pharmaceutical production. Despite encouraging advancements widespread adoption remains limited by economic constraints regulatory gaps and limited clinical evidence. Addressing these barriers through technological innovation largescale studies and life-cycle sustainability assessments is essential to translate hydrogen’s full potential into clinical and industrial practice. Responsible adoption of green hydrogen is poised to reshape the clinical approach to global health and enhance the quality of life for people worldwide.

This study presents an experimental investigation of a direct injection ammonia-fuelled engine using hydrogen pre-chamber jet ignition. All tests have been conducted in an optically accessible combustion chamber that is installed in the head of a single-cylinder engine. The effect of ammonia injection timing on ignition and combustion characteristics was investigated with the timing varied from 165 CAD BTDC to 40 CAD BTDC. The experiments were conducted with a fixed spark timing of 14 CAD BTDC while ammonia injection duration was adjusted to maintain a main chamber global equivalence ratio of 0.6. Two pre-chamber nozzle configurations a single-hole and a multi-hole were tested. The results show that the later NH3 injection timing (40 CAD BTDC) significantly improved combustion with a peak in-cylinder pressure of 80 bar measured compared to a peak in-cylinder pressure of 50 bar with earlier injection (165 CAD BTDC). This study indicates the importance of optimising ammonia injection timing in order to enhance combustion stability and efficiency. The hydrogen pre-chamber jet ignition combined with a late ammonia injection is a promising approach for addressing the combustion challenges of ammonia as a zero-carbon fuel for maritime applications.

Underground hydrogen storage (UHS) is a relatively new technology that demonstrates notable potential for the efficient storage of large quantities of green hydrogen. Its large-scale implementation requires a comprehensive understanding of numerous factors including safe and effective storage methods as well as overcoming various thresholds and challenges. This article presents strategies for accelerating the implementation of this technology identifying the thresholds and challenges affecting the development and future scale-up of UHS. It characterises challenges and constraints related to geology (including the type and geological characterisation of structures hydrogen storage capacity and hydrogen interactions with underground environments) the technological aspects of hydrogen storage (such as infrastructure management and monitoring) and economic and legal considerations. The need for the rapid implementation of demonstration projects has been emphasised. The identified thresholds and challenges along with the resulting recommendations are crucial for paving the way for the large-scale implementation of UHS. Addressing these issues will significantly influence the implementation of this technology post-2030.

H2 is increasingly recognized as a cornerstone of global decarbonization strategies including in hard-toabate sectors such as aviation. Its large-scale applicability remains limited owing to the limited diversity and maturity of low-carbon production pathways. Approximately 96% of global H2 production originates from non-renewable sources primarily through steam methane reforming (SMR) which remains the most commercially established route. Another critical barrier to the substitution of conventional aviation fuels lies in hydrogen storage as the current volumetric energy density and cryogenic storage requirements render onboard integration impractical for most aircraft configurations. To address these challenges this study developed a techno-economic and environmental benchmarking framework that compares conventional thermal reforming technologies (SMR autothermal and POX) with emerging electrochemical routes (water electrolysis and alcohol electro-oxidation) highlighting their potential roles in the transition toward sustainable aviation fuels (SAF). By normalizing efficiency energy intensity CO2 emissions and cost (USD kg 1 H2 and USD GJ 1 ) this study quantifies the trade-offs that define current and emerging pathways. SMR remains the industrial baseline (70%–85% thermal efficiency 1–2 USD kg−1 H2 9–12 kg CO2 kg−1 H2) whereas ethanol-based electrochemical reforming operates 0.3–0.9 V below conventional electrolysis achieving up to 40% lower electrical energy demand (∼2.4 kW h Nm−3 H2 with near-zero direct emissions. A sensitivity analysis demonstrates that a 60% reduction in catalyst cost or electricity prices below 0.03 USD (kW h)−1 could make electrochemical reforming cost-competitive with SMR. This study consolidates fragmented knowledge into a comprehensive roadmap that links catalyst performance and technology readiness for aviation decarbonization by integrating engineering metrics with policy and infrastructure perspectives to identify realistic transition pathways toward sustainable hydrogen and hybrid aviation fuels.

Hydrogen handling equipment suffers from interaction with their operating environment which degrades the mechanical properties and compromises component integrity. Hydrogen-assisted cracking is responsible for several industrial failures with potentially severe consequences. A thorough failure analysis can determine the failure mechanism locate its origin and identify possible root causes to avoid similar events in the future. Postmortem fractographic analysis can classify the fracture mode and determine whether the hydrogen-metal interaction contributed to the component’s breakdown. Experts in fracture classification identify characteristic marks and textural features by visual inspection to determine the failure mechanism. Although widely adopted this process is time-consuming and influenced by subjective judgment and individual expertise. This study aims to automate fractographic analysis through advanced computer vision techniques. Different materials were tested in hydrogen atmospheres and inert environments and their fracture surfaces were analyzed by scanning electron microscopy to create an extensive image dataset. A pre-trained Convolutional Neural Network was finetuned to accurately classify brittle and ductile fractures. In addition Grad-CAM interpretability method was adopted to identify the image regions most influential in the model’s prediction and compare the saliency maps with expert annotations. This approach offered a reliable data-driven alternative to conventional fractographic analysis.

The recent updates to the Single Day-Ahead Coupling (SDAC) framework in the European energy market along with new rules for providing manual frequency restoration reserve (mFRR) products in the Nordic Energy Activation Market (EAM) have introduced a finer Market Time Unit (MTU) resolution. These developments underscore the growing importance of flexible assets such as power-to-hydrogen (PtH) facilities in delivering system flexibility. However to successfully participate in such markets well-designed and accurate bidding strategies are essential. To fulfill this aim this paper proposes a Mixed Integer Linear Programming (MILP) model to determine the optimal bidding strategies for a typical PtH facility accounting for both the technical characteristics of the involved technologies and the specific participation requirements of the mFRR EAM. The study also explores the economic viability of sourcing electricity from nearby wind turbines (WTs) under a Power Purchase Agreement (PPA). The simulation is conducted using a case study of a planned PtH facility at the Port of Hirtshals Denmark. Results demonstrate that participation in the mFRR EAM particularly through the provision of downward regulation can yield significant economic benefits. Moreover involvement in the mFRR market reduces power intake from the nearby WTs as capacity must be reserved for downward services. Finally the findings highlight the necessity of clearly defined business models for such facilities considering both technical and economic aspects.

For five decades photocatalysis has promised clean hydrogen from solar energy yet a persistent “efficiency ceiling” linked to fundamental challenges including the trade-off between light absorption and redox potential in single-component materials has hindered its practical application. This review illuminates three key paradigm shifts overcoming this challenge. First we examine Z-scheme and S-scheme heterojunctions which resolve the bandgap dilemma by spatially separating redox sites to achieve both broad light absorption and strong redox power. Second we discuss replacing the sluggish oxygen evolution reaction (OER) with value-added organic oxidations. This strategy bypasses kinetic bottlenecks and improves economic viability by co-producing valuable chemicals from feedstocks like biomass and plastic waste. Third we explore manipulating the reaction environment where synergistic photothermal effects and concentrated sunlight can dramatically enhance kinetics and unlock markedly enhanced solar-to-hydrogen (STH) efficiencies. Collectively these strategies chart a clear course to overcome historical limitations and realize photocatalysis as an impactful technology for a sustainable energy future.

China is developing renewable energy bases (REBs) in the desert and Gobi regions. However the intermittency of renewable energy and the temporal mismatch between peak renewable generation and peak load demand severely disrupt the power supply reliability of these REBs. Hydrogen storage technology characterized by high energy density and long-term storage capability is an effective method for enhancing the power supply reliability. Therefore this paper proposes a REB planning model in the desert and Gobi regions considering seasonal hydrogen storage introduction as well as electricity-carbon-hydrogen markets trading. Furthermore a combination scenario generation method considering extreme scenario optimization is proposed. Among which the extreme scenarios selected through an iterative selection method based on maximizing scenario divergence contain more incremental information providing data support for the proposed model. Finally the simulation was conducted in the desert and Gobi regions of Yinchuan Ningxia Province China primarily verifying that (1) the REB incorporating hydrogen storage can fully leverage hydrogen storage to achieve seasonal and long-term electricity transfer and utilization. The project has a payback period of 10 years with an internal rate of return of 13.30% and a return on investment of 16.34% thus showing significant development potential. (2) Compared to the typical battery-involved REB the hydrogen-involved energy storage facility achieved a 59.39% annual profit a 10.98% internal rate of return a 14.93% return on investment and a 1.51% improvement in power supply reliability by sacrificing a 52.49% increase in construction cost. (3) Compared to REB planning based only on typical scenarios the power supply reliability of REBs based on the proposed combination scenario generation method improved by 8.58%.